A04_Attachment_A_North_Breton_Island_Phase_3_Planting_Restoration_Plan_0001.docx

North Breton Island Phase 3 Planting Restoration Plan

1. INTRODUCTION

North Breton Island is an approximately 422-acre barrier island located approximately 62 miles southeast from the metropolitan city of New Orleans, Louisiana (LA). North Breton Island is within the southern portion of Breton NWR in Plaquemines Parish, LA. North Breton Island is one of the most important barrier islands in LA. It provides habitat for one of the largest waterbird colonies in the state, including one of the largest rookeries for brown pelicans. The island also provides crucial protections for mainland LA, including the City of New Orleans, from storm surge and wave impacts.

North Breton Island had minimal direct damage from the Deepwater Horizon oil spill, however the spill caused ecosystem level damages to bird populations and Breton Island was an ideal location to provide additional nesting habitat to contribute to restoring the overall damages to birds from the spill. As part of the Deepwater Horizon Oil Spill Natural Resource Damage Assessment and Restoration (NRDAR) program, the Department of the Interior, through the U.S. Fish and Wildlife Service (Service) was tasked with mitigating environmental damaged caused by the spill. The effort includes restoring beaches, dunes, and back-barrier marsh habitats in Louisiana, in part to increase the populations of bird species impacted by the spill. The Louisiana Outer Coast Project - North Breton Island Component is a part of that effort.

This Restoration Plan outlines the objectives of Phase 3 of planting efforts at North Breton Island, including the installation of supplemental or replacement sand fencing.

2. RESTORATION AND ENHANCEMENT ACTIVITIES

2.1 Overview

The plantings at North Breton Island under the Phase 3 Planting effort will be split between four Restoration Areas (See Figure 1). The four Restoration Areas are as follows:

1. Avicennia germinans Restoration Area

2. Spartina alterniflora Restoration Area

3. Spartina patens Restoration Area

4. Mixed Species Back Dune Restoration Area Each Restoration Area will be planted using different species and with different spacing as outlined in this document and in the Technical Specifications of the “North Breton Island Restoration Project – Phase 3 Planting and Sand Fence Installation” Performance Work Statement.

Figure 1. Restoration Areas

2.2 Avicennia germinans Restoration Area

Within the Avicennia germinans Restoration Area, only Avicennia germinans will be planted. It will be planted throughout the entirety of the Restoration Area using a 3ft-by-3ft grid as shown in Figure 2.

Figure 2. Avicennia germinans spacing diagram

2.3 Spartina alterniflora Restoration Area

Within the Spartina alterniflora Restoration Area, only Spartina alterniflora will be planted. It will be planted throughout the entirety of the Restoration Area using a 3ft-by-3ft grid as shown in Figure 3.

Figure 3. Spartina alterniflora spacing diagram

1.1 Spartina patens Restoration Area

Within the Spartina patens Restoration Area, only Spartina patens will be planted. It will be planted throughout the entirety of the Restoration Area using a 3ft-by-3ft grid as shown in Figure 4.

Figure 4. Spartina patens spacing diagram

1.1 Mixed Species Back Dune Restoration Area

Within the Mixed Species Back Dune Restoration Area, a mixture of Spartina patens, Paspalum vaginatum, and Sporobolus virginicus will be planted. It will be planted in six (6) separate plots distributed along the length of the island adjacent to the island’s dune crest and previous plantings (see Figure 1). Each of the plots will be 1.92 acres, with a length and width of approximately 289 ft. The plots will be planted with a total of 57 rows, with approximately 19 rows for each species (see Figure 5). Based on estimates, there should be approximately 16 or 17 excess plants for each species per plot, in which case those plants should be used to widen the closest rows of the same species. The 19 rows closest to the dunes and furthest from the shoreline will be planted entirely with Sporobolus virginicus. The next 19 rows that are in the middle of the plot will be planted entirely with Spartina patens. Finally, the 19 rows that are closest to the shoreline and furthest from the dunes will be planted with Paspalum vaginatum (See Figure of rows). Within each row there will be 5ft between each plant and there will be 5ft between each row, so that a 5ft-by-5ft grid of plants is created (See Figure 6)

Figure 5. Mixed Back Dune Plot Row Layout Diagram

Figure 6. Mixed Back Dunes Species spacing diagram

2.4 Sand Fencing

Along the center of the island runs an approximately 15,000 LF dune crest. Between 2020 and 2022 fill was placed on the island to increase its elevation and area. After fill was placed, sand fencing was installed along the dune crest to ensure the stability and continued growth of the created dunes (see Figure 7). Since then, portions of the sand fencing have degraded or been completely buried by sand. As such, the Government wants to supplement the previously installed dune fencing with additional rows of sand fencing at targeted areas with the intent to install between 6,120 LF and 7,500 LF in total.

The newly installed fencing will fall within 200 feet of either side of the already existing fencing or dune crest (see Figure 8). Runs of sand fencing will be at most 450 LF, with a 30ft overlap between a run of fencing and the next run of fencing (See Figure 9). Throughout the 30ft overlap there should be an approximately 3ft gap of distance between the two runs of sand fencing, except every 5th overlap should have an 8ft gap. The 8ft gap is to allow transit of vehicles and other equipment when necessary. Sand fencing will run parallel to the existing dune crest. Because conditions on the island may change between the time of drafting this restoration plan and implementation, the final selection of sand fencing areas will be completed at least 60 days prior to the Contractor’s scheduled date for mobilization to the island.

Figure 7. Existing Sand Fencing

Figure 8. Supplemental Sand Fencing Area

Figure 9. Supplemental Sand Fencing Diagram image3.jpeg image4.jpeg image5.jpg image6.jpeg image7.png image8.png image9.jpg image1.png image2.jpeg